PROJECT SUMMARY As the leading cause of preventable death and disease in the United States, smoking poses substantial health risks to men and women. However, women are more vulnerable than men to some of the negative health consequences of smoking, such as heart disease, and they experience some sex-specific effects, including altered fertility and menstrual function, stillbirth, and cervical cancer. Compared to men, women also have more difficulty maintaining long-term abstinence and report greater craving and withdrawal-related distress (negative smoking-related states). Moreover, the reinforcing effect of smoking to ameliorate negative states (i.e., negative reinforcement), as well as the expectancies of such reinforcement, may contribute more to the failure of women vs. men to maintain abstinence from smoking. Although these negative states and their relief by smoking contribute to relapse, the neural mechanisms driving the male-female differences in these behavioral states remain unknown. Understanding them can help guide the development of personalized smoking cessation therapies, especially those that include brain-stimulation techniques that rely on knowledge of relevant functional anatomy of the brain. The goal of this project, therefore, is to advance basic science and clinical/translational studies of male- female differences in important determinants of failure in smoking cessation ? cigarette craving, negative states during withdrawal, and the negative reinforcement produced by resumption of smoking. Male and female, daily smokers (overnight abstinent) will be tested in two sessions, one before and one after they smoke the first cigarette of the day. In both the pre- and post-smoking sessions, the participants will complete self-report measures of cigarette craving, withdrawal and negative affect, and will perform a test of sustained attention, a cognitive function that is impaired in abstinent smokers and improved by resumption of smoking. Each session also will include fMRI both during the resting state and in conjunction with a craving-induction paradigm. Resting-state functional connectivity measures will focus on regions and circuits that have been linked with negative smoking-related states. These measures will include seed-based assessments of connectivity of the insula, which has been implicated in cigarette craving, and the relative connectivity strength of large-scale brain networks. Brain activation during cue-induced craving, a measure that is predictive of smoking-cessation treatment outcomes, will also be examined. The overall goal of this work is to identify neural substrates that underlie observed male-female differences in negative smoking-related states and their relief by smoking. This work will provide novel, critical data that will advance our knowledge of male-female differences, and will inform the development of personalized smoking cessation therapies.